Clinical classification and medical treatment options in childhood glaucoma.

IOP is the most variable diagnostic as it could be due to multiple factors (tonometer type, ocular movements, patient cooperation, anesthesia or corneal condition). Reference tonometry is Goldmann’s tonometer, although the Perkins tonometer (Haag-Streit AG, Bern, Switzerland) was utilized on multiple occasions as it enables IOP readings in supine position and with uncooperative patients. Other tonometers such as Tono-Pen (Reichert Ophthalmic Instruments, Depew, NY, USA),2,3 pneumotonometer (Ocular Response Analyzer,